Intestinal epithelial cell proliferation, differentiation, and apoptosis play important roles in intestinal development, maintenance, and recovery from tissue damage. In addition, epithelial cells in the pig intestine have notably high energy demands due to the rapid renewal of the epithelium (within few days). It has been reported that the activities of key metabolic enzymes in enterocytes changed during the suckling-weaning transition in pigs. However, the effect of early weaning on the metabolism of enterocytes along the crypt-villus axis has not yet been elucidated.

Recently, a study cooperated by Dr. XIONG Xia and Dr. YANG Huangsheng from Institute of Subtropical Agriculture, Chinese Academy of Sciences (ISA)has found that early-weaning differentially affect the expression of proteins involved in energy production of enterocytes along the jejunal crypt-villus axis.

In this study, researchers used a total of 16 piglets from 8 litters. One group of piglets was nursed by sows until age 21 days, and another group was weaned at age 14 days and then fed creep feed instead of breast milk for 7 days. Dr. Xiong investigated the metabolism of enterocytes along the crypt-villus axis in jejunum of early-weaned and suckled pigs by iTRAQ liquid chromatography coupled with tandem mass spectrometry(LC-MS/MS) proteomics. Their research results showed that proteins involved in the tricarboxylic acid cycle, ?oxidation, and the glycolysis pathway were significantly downregulated in the upper and middle villus of the early-weaned group. However, proteins involved in glycolysis were significantly upregulated in crypt cells.

Dr. XIONG also analyzed that weaning altered the expressions of proteins involved in energy production (amino acids, glucose, and fatty acid metabolism)may further affect the functions of epithelial cells, which further reduced the digestibility of energy and energy supply. In addition, expression trends of the proteins involved in the mTOR signaling pathway suggest that weaning may decrease protein synthesis in villus and crypt epithelial cells, which corresponds to an adaptation of the gut to the weaning diet.

In summary, this work found that early-weaning differentially affect the expression of proteins involved in energy production of enterocytes along the jejunal crypt-villus axis. Further study is going on to conducted to improve energy supply to weaning piglets, thus improving intestinal functions.

This work was supported by supported by National Natural Science Foundation of China, State Key Laboratory of Animal Nutrition, Knowledge Innovation Program of Institute of Subtropical Agriculture, Chinese Academy of Sciences and the Chinese Academy of Sciences Visiting Professorships for Senior International Scientists. Details can be found at http://www.ncbi.nlm.nih.gov/pubmed/26045611